I didn't show pulling the instrument cluster out because I had the extra cluster and decided not to pull mine out and put it right back in just for this. Sorry.

The hardest part is getting the headlight knob off. BEFORE DOING ANYTHING MAKE SURE YOU GAS TANK IS COMPLETELY FULL AND TAKE A PICTURE OF WHAT THE GUAGES ARE READING WHILE THE CAR IS IDLING AT FULL RUNNING TEMPERATURE, you'll see why later in the post.

With the car idling Take a clear picture of what the gauges

Remove the cluster from the dash.

Once you have both clusters in front of you look at the back.

The pic below is the cluster from the back. you'll see 6 Gold torx screws. Remove these.

Once they're out you can pull the White cover off and this is what you'll see.

This circuit board is just pushed down onto the studs sticking out of the back of the cluster. Gently pull up on the circuit board and it should slide off of them. The pics below is with the circuit board off, you can clearly see the posts it slides onto.

Just switch your stock GT circuit board onto the Bullitt cluster by pushing it down onto the studs until it's seated firmly. Then put the White backing plate back on with the 6 torx screws.

You're done with that part of it.

This next part is just for making sure that the gauges are reading properly:

Remove the clear lens from the front of the cluster.

Put the cluster back in the dash and hook up the connectors. DO NOT REPLACE ALL THE DASH PIECES YET

Now, hold the trip button down on the cluster while starting the car, keep holding it down until it says "test" in the digital readout, then let up on the button. This puts the cluster in diagnostic mode. Each time you press the trip button it will give you a different reading in the digital readout. Keep pressing it until you see "tach", the rpm should be reading just to the right of it. With the car idling see if the gauge matches the digital reading. If so, you're good. If not you can gently pry up on the needle and pull it off. Then put it back on so it reads the same as the digital readout.

Now, since you filled up you tank and took a picture before you started this, you can look at the pic and see if the fuel, temp and oil gauges are reading in the same spot. Make sure the car is idling at full running temperature, now compare those gauges now to what they were in the pic of the old cluster. If the are different, remove the needles and put them where they should be reading.

Once all of this is done and everything is good. Go ahead and put everything back together. You should be good to go.

AdRock. http://www.lonestarstangs.com/forum/install-bullit-guages-99-04-gt-38411.html